What has happened to Celine Dion?

In 2008, at age 40, she looked pretty good:

In 2015, at age 47, she already had the weird lines-in-the-neck thing going on, but otherwise looked okay:

Now take a look at her at age 51:

Her representatives were asked about her appearance, and were told that she lost a lot of weight as a result of depression from her husband's death. (Her husband was a huge fish in the big games in Bellagio, by the way.)

Even if that's true, couldn't she take some kind of weight gain supplements to reverse this?

I am guessing most 51 year old women who have been severely underweight most of their adult lives wouldn’t look much better. It is just something we don’t see very often.

I smoke color purple
I'm up in here feeling like silly
Nappy ass dreads, what's that you say?
Watch your mouth, Milli Vanilli
You can get snaked, you can get faked
I'll buy the bitch that you feeling
'Cause you thought that she was an angel
That bitch ain't no angel, I treat her halo like a Frisbee

For some people 10+ years looks like 20. I know myself personally I look back 10 years and see a difference where as the 10 before I didn't at all.
Add to it as mentioned her weight and stress, she look about what Id expect without plastic surgery.
No one disagrees with you Todd, she shows her age and then some for sure.
Nip Tuck required with all that cash inside 4 years Id imagine.

For some people 10+ years looks like 20. I know myself personally I look back 10 years and see a difference where as the 10 before I didn't at all.
Add to it as mentioned her weight and stress, she look about what Id expect without plastic surgery.
No one disagrees with you Todd, she shows her age and then some for sure.
Nip Tuck required with all that cash inside 4 years Id imagine.

I think she looks astoundingly old for 51. I don't know how old you are, but I'm 47, so she is in my general age group. I also know what women my age look like. While there's a lot of variance at this point, I know very few women personally who look as old as Celine does.

I think something external is to blame for this. Looks like a combination of anorexia (maybe brought on by depression) and something else.

This is beyond the situation where a formerly attractive celebrity of the past just doesn't look good after 50.